Boundary layer eliminator



Oct.'15, 1968 H. R. PATTERSON, JR 3,405,884

BOUNDARY LAYER ELIMINATOR Filed Sept. 8, 1966 PRIOR ART INVENTOR. #EA/k Y 1?. 51776250 Je.

y M ATTORNEYS United States Patent 3,405,884 BOUNDARY LAYER ELIMINATOR Henry R. Patterson, Jr., West Chester, Pa., assignor to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Continuation-impart of application Ser. No. 342,091,

Feb. 3, 1964. This application Sept. 8, 1966, Ser.

8 Claims. (Cl. 242-76) ABSTRACT OF THE DISCLOSURE A guide roll assembly for the traveling paper web including means for delivering such a traveling paper Web as for example used on a paper roll winder, and a freely .rotatable guide roll engaging the web with the surface partially wrapped thereby and being driven thereby. The freely rotatable guide roll is provided with a plurality of venting means in the surface thereof, such as extending grooves of certain configurations, receiving the air carried over the roll surface body by the oncoming web and purging the same therebetween.

This is a continuation-in-part application of US. Ser. No. 342,091, filed Feb. 3, 1964, now abandoned.

The present invention relates to improvements in guide roll assemblies having a guide roll supporting a traveling paper web with a light web tension therein with the roll being driven in rotation by the contact of the web against its surface.

In a high speed paper handling mechanism wherein wide webs of paper pass over undriven guide rolls wherein there is a light tension in the paper web, air tends to be carried onto the roll surface by the traveling web, forming a cushion. The amount of such a cushion is a function of mechanism speed. This tends to cause marking of the paper surface and web tension variations, both of which are highly undesirable. The air cushion building up on the surface of the undriven roll tends to make the paper skid causing paper surface marking, variation in tension, and deviation in the path of movement of the paper web. The cushion of air also tends to permit the undriven roll to slightly slow its speed and when the air cushion decreases the traveling web surface will again contact the roll and relative movement between the roll surface and web will cause marking of the paper surface.

It is accordingly an object of the present invention to provide an improved guide roll assembly for handling traveling paper webs with light web tension wherein undesirable surface marking of the paper is eliminated.

Another object of the invention is to provide an improved guide roll driven by contact with a paper web wherein the tendency to build up a cushion of air between the web and roll surface is eliminated and the roll thus will continue to have good contact with the traveling paper web and will continue to hold the web accurately in its path of movement and will continue rotating with a surface speed substantially at the exact speed of movement of the paper web.

A further object of the invention is to provide an improved paper web guide arrangement for use with paper web winders avoiding the necessity of providing expensive drives to maintain the guide rolls at the exact speed of paper web travel.

ice

A still further object of the invention is to provide an improved guide roll structure which eliminates the formation of air bubbles between the web and roll and improves sheet tracking at light tensions with or without driving of the roll.

A still further object of the invention is to provide an improved guide roll structure which has a relatively low mass while retaining sufiicient strength to support the web under constant tension.

The invention contemplates providing a guide roll assembly for a paper web including means for delivering a traveling paper web, such as used in a paper roll Winder, and a freely rotatable guide roll engaging the web with the surface partially wrapped thereby and being driven thereby, and a plurality of venting means in the surface of the roll such as extending grooves of certain configuration receiving the air carried over the roll surface by the oncoming web.

Other objects, advantages and features will become more apparent with the teaching of the principles of the present invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings, in which:

FIGURE 1 is a schematic view showing rolls as arranged in a winder machine for handling a traveling paper web embodying a guide roll constructed and operating in accordance with the principles of the present invention;

FIGURE 2 is an enlarged schematic elevational view showing the effect of air on structures heretofore used;

FIGURE 3 is a schematic detailed sectional view taken through a roll constructed according to the present invention;

FIGURE 4 is a fragmentary plan view of the end of the roll of FIGURE 3;

FIGURE 5 is a fragmentary plan View of a modified form of guide roll;

FIGURE 6 is a fragmentary plan view of another form of roll; and

FIGURE 7 is a schematic fragmentary end elevational view of the roll of FIGURE 6.

As shown on the drawings:

FIGURE 1 shows a winder mechanism schematically with a paper roll 10- being wound supported on winder drums 11 and 12 with a rider roll 13 at the top. The winder drums 11 and 12 are driven by suitable means and a paper web W is delivered to the roll at relatively high speed. The web is received from suitable web supply means and is delivered as shown schematically by a roll 14 and passes over a guide roll 15. The guide roll 15 supports the span of web between the web delivery means in the form of the roll 14 and the web receiving means in the form of the drum 12. As will be appreciated by those versed in the art, the web is received by being unwound off a supply roll (not shown) before it passes onto roll 14 and for convenience the roll 14 may be referred to as the supply or delivery roll inasmuch as it transports the supplied or delivered web on to the guide roll 15. For satisfactory operation at high speeds the web span S must be accurately tracked and the guide roll 15 is a freely rotating roll having a small angle wrapped by the web and driven by surface engagement with the web. While the guide roll 15 is shown schematically in a location leading directly to the winder it will be appreciated that various other locations may be employed.

As shown in FIGURE 2, during high speed winding a boundary layer of air 17 squeezes between the undriven plain surfaced cylindrical roll 15 and the Web W. This layer of air 17 results in lost traction between the surface of the roll 15 and the web and a speed differential occurs when web contact is lost. During deceleration of the web the air cushion 17 is lost and the roll and web will again come in contact causing relative slippage bet-ween the web and roll surface. This results in sheet marking. This also results in tension variations in the web which is highly undesirable with respect to the operation of the winding drum 12 and the resultant roll 10.

The building up of the air cushion 17 also causes lateral skidding of the sheet causing it to deviate from its path which is highly undesirable as far as the operation of the winding mechanism is concerned.

Plain surfaced roll 15 has relatively substantial mass and once the web W has sufficiently driven the roll 15 to a substantially matching linear speed of the traveling web, the roll 15 will tend to continue at that relatively high speed from its resulting inertia. When the web W decelerates, as previously explained, and again contacts the roll surface, the inertia of the roll mass resists the change of speed and will cause scorching, slippage, and similar damage to the web which is highly undesirable as far as the finished paper product and the operation of the winding mechanism is concerned.

In accordance with the principles of the present invention, instead of providing a plain surfaced roll 15, a guide roll 16 is provided, FIGURES 3 and 4, which has imperforated recesses in the surface preferably in the form of extending grooves 18. The venting means may be axially extending grooves and ridges machined onto the surface of roll 16 or the grooves may be preformed onto a suitable cover which is then fitted onto the periphery of a suitable roll. The grooves 18 have an open top at the roll circumference and a closed bottom interior thereof so as to form an imperforate roll. As will be realized, in certain operations discrete recesses or bottomed holes may also be used. The air carried over the roll surface is vented by the grooves to ambient atmosphere (where discrete holes are used, the air is briefly compressed within the holes) permitting the web to maintain contact with the surface area between the openings and properly track in the proper direction.

It has been found that the grooves 18 must be of an axial dimension to prevent sheet marking and that the axial dimension of the grooves is preferably in the range of to inch, and the recesses should cover no more than 40% of a total surface of the roll in order to avoid sheet marking and provide adequate surface area for engagement between the roll surface and web. The arc of wrap of the roll by the web extends over an arc of between to 60.

The venting means, especially in the form of extending grooves, serve not only to vent the oncoming air from beneath the traveling web as it contacts the roll surface, but additionally reduce the overall mass of the roll so that it does not develop any substantial inertia. It is advantageous to use as light a mass as possible consistent,

with the strength requirements for supporting a traveling web under constant tension. To this end, imperforated guide rolls having extending grooves are uniquely well suited.

The grooves serve the dual function of removing a substantial amount of mass from. the roll and venting air from the underside of the web as it passes over the roll. As will be realized, the less mass that the guide roll has, the less its tendencies to mark the traveling web, as the roll will not be able to develop any great inertia which the web must overcome. As the grooves are bottomed and the roll still maintains a solid shell, at least at the inner extremity of the grooves, no substantial sacrifice of strength is necessary and materials presently being used for guide rolls can continue to be safely used. Further, the relatively narrow groove axial'dimensions allow suflicient land areas to fully support the web and vent the oncoming air.

FIGURES 5, 6 and 7 show an arrangement where the guide roll 22 (and alternatively guide roll 22, as shown in FIGURE 6) is provided with other configurations of grooves to permit the escape of air. The guide roll 22 is provided with grooves 23 (and alternatively grooves 23' as shown in FIGURE 6) which extend preferably the entire length and open at the end of the roll 22 as shown at 24 to provide escape channels. The grooves are prefer ably non-linear axially and certain forms of grooves are shown, and other groove forms may be employed which do not tend to shift the paper web axially relative to the guide roll. The present arrangement is employed at low web tensions in the range of less than 10 pounds perinch of web width.

It will be understood that patterns different than FIG- URES 5, 6 and 7 may be used such as other herringbone patterns, and parallel grooves which extend inwardly at an angle to the roll axis from both ends to meet at the midpoint of the roll surface, either extending generally axially or generally circumferentially.

. Thus it will be seen that I have provided an improved guide roll assembly for use with a winder mechanism or similar mechanism, which meets the objectives, advantages and features above set forth. The mechanism provides a solution to a problem which has arisen with high speed web winding and which occurs with low web tension.

The drawings and specification present a detailed disclosure of the preferred embodiments of the invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by the invention.

I claim as my invention:

1. In a guide roll assembly for paper web handling machines, the combination comprising, means receiving a traveling paper web, roll means engaging the traveling web with a span between said receiving and engaging means, an imperforated freely rotatable guide roll en gaging the web in said span throughout a relatively small arc, and a plurality of venting means in the surface of said guide roll purging air carried over the roll surface by the oncoming web, said venting means defining an open area at the roll periphery of not more than 40%.

2. In a guide roll assembly, a combination in accordance with claim 1 wherein the venting means comprises relatively narrow axially extending grooves receiving air carried over the roll surface by the oncoming web to avoid forming an air film lifting the web off said guide roll to avoid thereby marking the web.

3. In a guide roll assembly, a combination in accordance with claim 2, wherein the grooves have a Wavy nonlinear form.

4. In a guide roll assembly, a combination in accordance with claim 2, wherein the grooves have herringbone pattern substantially converging in the center of the peripheral surface of the guide roll.

5. In a guide roll assembly a combination in accordance with claim 2 wherein the grooves formed in the surface of the guide roll surface extend axially to the edge of the roll beyond the area of web contact for purging the air carried onto the surface of the roll by the oncoming web.

6. In a guide roll assembly for a paper web handling machine, the combination comprising, means receiving a traveling web of paper, roll means engaging the traveling web with a span between said receiving and engaging means, an imperforated freely rotatable idler guide roll engaging the web in said span with the roll surface partially wrapped thereby and being driven thereby, and a plurality of alternating ridges and grooves in the surface of said roll with the grooves receiving air carried over the roll surface by the oncoming web, said grooves having an open top at the roll circumference and a closed bottom, each groove extending on the roll surface so that when a first portion of the groove is beneath the Web on the roll and said portion is closed by the web spanning the ridges each side of another portion of the groove communicating with said first portion is free of being closed by the web and is exposed to the atmosphere so that air can escape from the open top of the groove to the atmosphere, said grooves defining an open area of not more than 40%.

7. In a guide roll assembly for a paper web handling machine the combination in accordance with claim 6 wherein the grooves are arranged so that a plurality of grooves are beneath the web at one time over the portion of the roll wrapped by the web and said grooves are substantially uniformly spaced on the roll surface.

8. In a guide roll assembly, a combination in accordance with claim 6 wherein the web wraps the guide roll surface throughout an arc of less than 60.

References Cited UNITED STATES PATENTS 2,404,159 7/ 1946 Barber. 2,717,037 9/1955 Goodwillie 242-76 X 2,980,356 4/1961 Beese et a1 242-66 X 3,174,670 3/1965 Zernov 226-190 X FOREIGN PATENTS 306,190 6/1918 Germany.

STANLEY N. GILREATH, Primary Examiner.

N. L. MINTZ, Assistant Examiner. 

